Macromolecules of the myocardial cell surface coat (glycocalyx) are being characterized. Their synthesis and turnover is being measured radioisotopically. An antibody to molecular myosin has been prepared and this will be used in an attempt to map the spatial relations of developing myofibrils within the intact myocardium. A colony of salamanders, Ambystema mexicanum, has been established. We intend to examine the molecular basis of the cardiac lethal gene. BIBLIOGRAPHIC REFERENCES: Satow, Y. and Manasek, F., Direct effects of trypan blue on cardiac extracellular macromolecule synthesis. Lab. Invest. 36:100-105, (1977). Manasek, F. J. and Cohen, A. M., Anionic glycopeptides and glycosaminoglycans synthesized by embryonic neural tube and neural crest. Proc. Natl. Acad. Sci. U.S.A. 74:1057-1061, (1977).